In general, IC card readers comprise guide means for guiding or positioning the card, optional means for verifying that a card is present in the reader, and is present in an appropriate position, and also contact elements for providing electrical connection with conducting pads on the IC card via which circuits are established to the apparatus including the IC card reader.
One such IC card reader is described in French patent No. 2 534 713. The guide means therein are surfaces associated with the structure of the reader. The presence of a card is verified by means of an end-of-stroke microswitch and the contact elements are resilient metal blades mounted in a frame of insulating material.
There are thus three independent parts, and assembly thereof is not described in detail. Unfortunately, such a structure requires the various parts to be assembled accurately, and not only is this expensive, but given the accumulated assembly tolerances on the various parts, this may also lead to it being impossible, in practice, to satisfy the requirements of the user. In addition, the actual assembly is left to the manufacturer of the apparatus, whereas such a manufacturer would find it appreciably easier to use a unit component which did not require any special precautions.
More precisely, the force exerted by each of the contact elements for connection to the IC card when pressing against a conducting pad of a card can be expressed by an equation of the type f=kx, where k represents the resilient characteristics of the contact element, and x represents the deflection to which said contact element is subjected in the presence of a card. This force f must be obtained relatively accurately, i.e. with relatively narrow tolerances, since if it is too small then there are problems of contact resistance, and if it is too large, then there are problems of wear both with the contact elements and with the cards. Further, the force exerted by all of the contact elements together on a card give rise to a force retaining the card in the apparatus, and this overall force is also subject to narrow tolerances. Unfortunately, the value of k may vary in the course of industrial manufacture by as much as .+-.25%, for example. Although this amount of tolerated variation could be reduced to a smaller value, that would require expensive measures to be undertaken. If it is desired that the force f remain within limits which are not much wider than those allowed to the factor k, then x must be defined as narrowly as possible. In other words accurately positioning the card relative to the contact elements is of capital importance.
The object of the invention is thus to provide a unit component called herein a "contact frame", said component solving the problems of assembly tolerances and making it possible to satisfy the severest card positioning requirements at reduced cost, said component being very simple to use.